Author of Administrative Sanctioning Law (Revista dos Tribunais; 1st edition in 2000, 11th edition in 2026), of Theory of Administrative Improbity: public mismanagement, corruption, inefficiency (Revista dos Tribunais; 1st edition in 2007, 6th edition in 2022) and of Administrative Improbity: Observations on Law 8,429/92 (Síntese; 1997, 2nd edition in 1998).
Co-author, with Alexandre Pinheiro dos Santos and Julya Sotto Mayor Wellisch, of Capital Markets: Sanctioning Regime (Saraiva, 2012). Coordinator, with Marcos Juruena Villela Souto, of Administrative Law: studies in honor of Diogo de Figueiredo Moreira Neto (Lumen Juris, 2006), and coordinator of Sanctioning Law: National Financial System (Fórum, 2007). The editions, covers and references of each work are in Books and legal works.
He began teaching in 1992, at the Torres campus of Ulbra, when he was a public prosecutor in that judicial district. The table below lists the institutions where he has taught or collaborates, with the city, level of teaching, subjects, period and nature of the activity.
| Institution | City | Level | Subjects | Period | Nature |
|---|---|---|---|---|---|
| Schools of the Judiciary of the TRF4 (Emagis) and the TRF2 (Emarf) and the School of the Judiciary of the State of Rio de Janeiro (EMERJ) | Porto Alegre (RS) and Rio de Janeiro (RJ) | Training and continuing education of judges | Courses, special classes and symposia on administrative sanctioning law and improbity | Emagis: 2012; Emarf: 2012 and 2014; EMERJ: 2018, 2019 and 2021 | Collaborating professor, in courses and events |
| Higher School of the Judiciary (Ajuris) | Porto Alegre (RS) | Postgraduate studies in Criminal Law and refresher courses for judges | Criminal Law; liability of public agents and administrative improbity | Refresher courses in 2001 and 2018 | Teaching |
| Federal University of Rio Grande do Sul (UFRGS) | Porto Alegre (RS) | Lato sensu postgraduate studies (specialization in Criminal Law and Criminal Policy) | Administrative Sanctioning Law | 2008–2010 | Permanent professor of the course |
| Higher School Foundation of the Public Prosecution Service of Rio Grande do Sul | Porto Alegre (RS) | Lato sensu postgraduate studies (specializations in Constitutional Law and in Diffuse and Collective Interests) | Constitutional Administrative Law and Defense of Public Assets | 2006–2010 | Collaborating professor |
| Federal University of Rio Grande do Sul (UFRGS), Graduate Program in Law | Porto Alegre (RS) | Master's and doctoral programs | Principles of Administrative Sanctioning Law, a course he created | 2004–2010 | Collaborating professor |
| Pontifical Catholic University of Rio Grande do Sul (PUC-RS) | Porto Alegre (RS) | Undergraduate | Administrative Law, Criminal Law and Institutions of Public and Private Law | 1995–2003 | Assistant professor |
| Lutheran University of Brazil (Ulbra), Torres campus | Torres (RS) | Undergraduate | Introduction to the Study of Law | 1992 | Teaching |
| Pontifical Catholic University of Rio Grande do Sul (PUC-RS), Uruguaiana campus | Uruguaiana (RS) | Undergraduate | — | — | Teaching |
| Pontifical Catholic University of Rio Grande do Sul (PUC-RS) | Porto Alegre (RS) | Lato sensu postgraduate studies | Criminal Law | — | Teaching |
| University of the Sinos Valley (Unisinos) | — | Lato sensu postgraduate studies | Criminal Law | — | Teaching |
He took part in the founding of the IIEDE as vice president, at the seminar The New Law of the State, held in Porto Alegre from 6 to 8 October 2003. Eduardo García de Enterría was the honorary president of the institute. He assumed the executive presidency in 2007.
As head of the IIEDE, he coordinates seminars with Brazilian and foreign jurists, among them The New Law of the State (Porto Alegre, 2003); seminars on Good Governance in the National Financial System (2007 and 2008); Infractions and Sanctions in Regulated Public Services (Brasília, 2008, 2010 and 2012); Regulatory Due Process before CADE (Rio de Janeiro, 2013); international seminars in honor of Juan Carlos Cassagne (2020) and Tomás-Ramón Fernández (2021); Administrative Sanctioning Law in Comparative Perspective (2020); Contemporary Administrative Sanctioning Law, with the CVM (Rio de Janeiro, 2023); and New Paradigms of Compliance in Brazil, with BNDES (Rio de Janeiro, 2024). Programs and recordings are in the section Seminars of the site.
On leaving the Public Prosecution Service in February 2006, he became legal director of the Bozano Group, a position he held until 2007. On 27 March 2007 he founded Medina Osório Advogados in Porto Alegre, which opened offices in Rio de Janeiro in 2011 and in Brasília in 2017. He is the firm's managing partner.
Since 2019 he has chaired the Special Commission on Administrative Sanctioning Law of the Federal Council of the OAB, created that year, and was reappointed in 2022 and 2025. He is a councilor of the Movement for the Defense of the Legal Profession (MDA), reappointed in 2025, and was inducted into the Brazilian Bar Institute (IAB) in 2025.
In December 2021, he was one of the jurists invited by the National Consumer Secretariat to support the special commissions of the National Consumer Protection Council created that year, on electronic fraud, accessibility for consumers with disabilities, and legal certainty in the application of administrative sanctions. He is a peer reviewer for the Revista de Direito Administrativo (RDA), published by FGV, and was a peer reviewer for the Revista CEJ, of the Center for Judicial Studies of the Federal Justice Council.
He served as Attorney General of Brazil, with ministerial rank, from 12 May to 9 September 2016. The appointment was published in the Diário Oficial da União of 13 May 2016.
Among the acts of his tenure were the filing, in May 2016, of administrative improbity actions against companies and individuals investigated in Operation Car Wash, seeking reimbursement and fines of about R$ 12 billion; AGU Ordinances No. 487 and No. 488, of 27 July 2016, which regulated the acknowledgment of claims, the waiver of the duty to contest and to appeal, and the withdrawal of judicial proceedings, and delegated to the Federal Attorney General the authority to approve judicial settlements; and the submission of a draft decree to regulate the Mediation Law (Law 13,140/2015) in the federal administration.
Before the Federal Supreme Court, the Office of the Attorney General spoke on his behalf in dozens of concentrated constitutional review actions, among them ADI 5508, in which he defended the validity of plea cooperation agreements entered into by police chiefs, a thesis accepted by the Court in 2018.
Between 2003 and 2005 he was deputy secretary of Justice and Security of Rio Grande do Sul.
Having placed first in the entrance examination, he took office as a public prosecutor on 30 December 1991. He served in the judicial districts of Torres, Uruguaiana and São Jerônimo and, in Porto Alegre, in the Partenon Regional Prosecutor's Office and the Environmental Protection Prosecutor's Office. In 2003 he was assistant prosecutor to the Attorney General of Justice.
During this period he published 23 theses in the proceedings of the State Congress of the Public Prosecution Service (1994–1998) and his first book, Administrative Improbity: Observations on Law 8,429/92 (1997), the fruit of his work in defense of public assets. He left the institution at his own request on 31 January 2006, after more than fourteen years of service.
According to the Spanish doctoral thesis database (TESEO), his thesis is the last of the nineteen supervised by García de Enterría. The academic relationship continued after the defense: Enterría wrote the preface to Theory of Administrative Improbity, a work derived from the thesis, and was honorary president of the IIEDE from the founding of the institute, in 2003, until his death in 2013.